23 - Neglect

Summary

Apatient with the neglect syndrome fails to report, respond or orient to, novel or meaningful stimuli presented to the side opposite a brain lesion (Heilman, 1979). If this failure can be attributed to either sensory or motor defects, the patient is not considered to have neglect.

The two basic mechanisms that are thought to be responsible for the failure to report, respond, or orient are defects in the systems that mediate sensory attention or motor intention. Whereas attentional defects may be associated with unawareness, intentional disorders may cause a failure to respond despite stimulus awareness. Attention and intention defects may occur in two domains: spatial and personal. Patients with neglect can also have spatial memory defects. This defect can be for new information or old memories (representational defects). This chapter describes tests that may be used to assess patients and behaviourally define these disorders. This chapter also discusses the pathophysiology underlying these disorders and their treatment.

Behavioural testing for the components of neglect

Tests for inattention and extinction

The attentional aspects of the neglect syndrome are detected by observing abnormal responses to sensory stimuli. Stimuli should be given in at least three modalities, somatesthetic, visual, and auditory, but other stimuli, such as gustatory and olfactory, may be used. Examiners often request immediate responses, however, delaying the response and using distractor techniques may help amplify the symptoms.

When testing with somatesthetic stimuli, one may control the intensity of a tactile stimulus by using Von Frei's hairs. However, fingers or cotton applicators are more convenient. Other cutaneous stimuli, such as pins, may be used. For bedside auditory testing, we use sounds made by either rubbing the fingers together or snapping them. When possible, perimetric and tangent screen studies should be used for testing visual fields. However, for bedside testing the confrontational method may be used; the examiner's finger movement can be used as the stimulus. A modified Poppelreuter diagram or written sentences may also be used.

These somatesthetic, auditory and visual stimuli should be presented to the abnormal (contralateral) side and to the normal side of the body in random order. If the patient responds normally to unilateral stimulation, simultaneous bilateral stimulation may be used. Unilateral stimuli should be randomly interspersed with simultaneous bilateral stimuli.